Magnetic Properties of Cr1/3NbS2

An intercalated 2H-type layer compound, Cr 1/3 NbS 2 , was investigated by magnetic and neutron diffraction measurements. It was found that this compound is a helimagnet with a very long period along the c -axis and with the spins in the c -plane. The magnetic behavior is similar to that of an easy-plane type ferromagnet except for the magnetization curve in the c -plane. The Curie temperature is 127 K. The saturation magnetization corresponds to 2.9 µ B /Cr. The uniaxial anisotropy constant, K 1 , is -1.46×10 6 ergs/cc at 4.2 K. The magnetizatiom curve in the c -plane shows a metamagnetic behavior, the critical field of which is as low as 1.5 kOe except near T c . Small angle scattering measurements showed a helical structure with Q =0.013 Å -1 (480 Å period). The helical spin structure and the metamagnetism is explained as due to the antisymmetric exchange interaction.